body {
    background-color: rgb(240, 244, 249);
}

#courseList {
    margin-top: 35px;
}

#content {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    grid-auto-rows: 250px;
    margin: auto 140px;
}

.div-relative {
    position: relative;
    width: 200px;
    height: 200px;
    margin-top: 10px;
    overflow: hidden;
}



/*最底层，图片*/
.bg1 {
    background-color: white;
    width: 200px;
    height: 200px;
    position: absolute;
}

/*中间层，蒙版*/
.bg2 {
    width: 200px;
    height: 200px;
    opacity: 0; /*颜色透明度*/
    background-color: #eee;
    position: absolute;
    transition: opacity .5s;
    -webkit-transition: opacity .5s;
}

/*最上层，详细信息*/
.bg3 {
    width: 200px;
    height: 200px;
    bottom: 0;
    background-color: black;
    opacity: 0;
    position: absolute;
    padding-left: 20px;
    padding-top: 50px;
    transition: opacity .5s;
    -webkit-transition: opacity .5s;
}

.bg3:hover {
    opacity: .7;
}

.bg3 h4 {
    font-weight: bold;
    color: white;
}

.bg3 p {
    line-height: 10px;
    color: white;
}


/*查询部分*/
label {
    font-size: 13px;
    font-weight: bold;
    color: whitesmoke;
}

[v-cloak] {
    display: none;
}

